1. Field of the Invention
The present invention relates to refiners especially useful for refining paper pulp, and is more particularly concerned with certain new and improved flexible refining disks for such refiners, and the method of making such disks.
2. Description of Prior Art
Conventional methods of refining paper stock, as it comes from beaters, digesters, or other pulping apparatus, generally involve passing the stock between rigid grinding or refining surfaces which break up the fibrous material and effect some further separation and physical modification of the fibers.
Substantial improvements in refiners for this purpose are disclosed in the copending application for patent of John B. Matthew and Edward C. Kirchner, Ser. No. 486,006 filed Apr. 18, 1983, now U.S. Pat. No. 4,531,618, issued July 30, 1985, and assigned to the same assignee as the present application. According to that application, the rigidity constraints typically theretofore required in rotary disk refiners is overcome and substantial improvements in structure and operation are attained by the provision of resiliently flexible refining surface-supporting disks permitting operating pressure responsive adjustment of the relatively rotating refining surfaces axially relative to one another for attaining optimum material working results from the refining surfaces. More particularly, the resiliently flexible refining surface-supporting means comprise annular disk-supporting ring-shaped refining surface plates of limited radial width which are mounted in sandwiching relation to margins of the disks while the opposite margins of the disks are equipped for fixed attachment in the refiner apparatus. The refining surface plates are secured to the disk margins by mechanical means comprising screws, but which may also comprise rivets. However, such mode of securement involves considerable machining such as drilling, tapping and securement of the fasteners. Certain thickness tolerance problems in these modes of securement diminish the desired tolerance precision in the disk assembly in the refiner. Precision is highly desirable for attaining optimum results in the close cooperation of the refining surfaces required for paper pulp refining. It is to the alleviation of such problems that the present invention is primarily directed.